kuykendall



y 1962 4 J. H. KUYKENDALL 3,032,684

- IGNITION SYSTEM Filed July 14, 1959 s Sheets-Sheet 1 T TO T 4 DISTRIBUTOR AND .l 8 SPARK g PLUGS T T To DISTRIBUTOR 4 AND SPARK PLUGS 5* i W INVENTOR.

JAMES H. KUYKENDALL BY $9M, MZW.

ATTORNEYS y 1962 J. H. KUYKENDALL 3,032,684

IGNITION SYSTEM Filed July 14, 1959 5 Sheets-Sheet 2 TO DISTRIBUTOR AND SPARK PLUGS T0 DISTRIBUTOR AND SPARK PLUGS INVENTOR. JAMES H. KUYKENDALL ATTORNEYS May 1, 1962 J. H. KUYKENDALL 3,032,684

IGNITION SYSTEM Filed July 14, 1959 5 Sheets-Sheet 5 I I i TO'DISTRIBUTOR AND F 5 SPARK PLUGS JAMES H. KUYKENDALL ATTORNEYS United rates Patent 3,032,684 IGNITION SYSTEM James H. Kuykeutlall, Summit, N.J., assignor to Tung- Sol Electric Inc, a corporation of Delaware Filed July 14, 1959, Ser. No. 827,045 9 Claims. (Cl. 315-183) This invention relates to an ignition system for internal combustion engines and has particular reference to an electronic circuit which uses no hot cathode vacuum tubes.

' The ignition system generally used at present comprises a primary circuit which includes a storage battery and breaker contacts which are run in synchronism with the engine power shaft. A secondary or high voltage circuit includes the secondary of a transformer, distributor points, and spark plugs. At slow speeds and a moderate compression ratio this system works well and has given good service in automobiles for many years.

The use of higher engine speeds and higher compression ratios places a greater strain on the breaker contacts which must break larger currents at a greater freuency. The higher compression ratios tend to reduce the life of the spark plugs because they must handle higher voltages and pass greater currents.

The present invention is designed to eliminate the above mentioned disadvantages by providing current amplification between the breaker contacts and the primary of the high voltage transformer. This reduces the current broken by the contacts. The invention also supplies high voltage to the distributor and spark plugs by the discharge of a storage capacitor which concentrates the spark and provides a steep wave front for each discharge.

The new ignition system for internal combustion engines includes a primary circuit having a pair of breaker contacts connected in series with a source of direct current in the input circuit of a semiconductor amplifier. The output of the amplifier is connected to the primary winding of a step-up transformer whose secondary is connected in series with a rectifier and a storage capacitor for receiving a charge each time the breaker contacts close. The discharge circuit includes the storage capacitor, a thyratron which is made conductive each time the breaker contacts open and the primary winding of a transformer whose secondary winding is connected to the distributor and spark plugs.

For a better understanding of the present invention, and of specific embodiments thereof, reference may be had to the following description taken in connection with the accompanying drawings of which:

FIG. 1 is a circuit diagram of the simplest form of ignition circuit embodying the invention;

FIG. 2 is a diagram similar to FIG. 1 but showing a direct connection to the base of the transistor amplifier for providing current feed back;

FIG. 3 is a diagram similar to FIGS. 1 and 2 but including a second transistor amplifier;

FIG. 4 is a circuit diagram similar to FIG. 2 but showing transformer coupling to the base circuit of the transistor amplifier for current feed back;

FIG. 5 is a circuit diagram similar to FIG. 2 but including an extra storage capacitor for providing additional current for the spark; and

FIG. 6 is a diagram similar to FIG. 2 but including means'for shaping the wave form delivered to the ignition coil.

In the simple ignition circuit of FIG. 1 a transistor amplifier, shown as a p-n-p transistor, is indicated at 2 with its emitter connected to the positive terminal of a battery 4, which may be the car carried storage battery, and its collector connected through the primary winding of a transformer 6 to the negative terminal of the ice battery 4. The base of the transistor 2 is connected through a resistor 8 and breaker points, diagrammatically indicated at 10, to the negative terminal of the battery 4. The emitter and base terminals of the transistor 2 are bridged by a high resistor 12. One secondary winding 14 of the transformer 6 is connected at one end to .the anode of a diode rectifier 16 and at its other end to the negative terminal of the battery. The second secondary winding 18 of the transformer 6, Wound oppositely to winding 14, has one end .connected through a resistor 20 to the control grid of a gas thyratron 22 and its other end connected to the negative terminal of the battery. The cathode of diode 16 is connected to one terminal of a capacitor 24 and to the anode of the triode 22. The cathode of triode 22 is connected to the negative terminal of the battery and the other terminal of capacitor 24 is connected through the primary of the ignition coil 26 to the negative terminal of the battery. The secondary winding of the coil 26 is connected in circuit with the distributor and spark plugs (not shown) of the car ignition system.

With the above described circuit, when the breaker contacts 10 close, the transistor 2 conducts causing current to flow through the primary of transformer 6. Charging current for the capacitor 24 is then delivered through the rectifier tube 16 and a relatively high voltage is built up at the anode of the thyratron 22. Tube 22 will not be firedbecause the grid thereof is held negative due to voltage induced in winding 18 of transformer 6. When the contacts 10 open the sudden reduction of current through the primary of transformer 6 causes a positive potential to be applied to the grid of tube 22 and consequent discharge of condenser 24 through the triode 22 and through the primary winding of the ignition coil 26.

It will be apparent that the system, by placing the breaker contacts in the low current input circuit of the transistor, insures longer life for these contacts. The circuit increases the rise time of the voltage across the spark plugs and eliminates danger of continuous discharge through any of the tubes. Sufficient energy is provided to charge the condenser 24 in the available time at maximum engine speed. Upon opening of the breaker contacts the voltage of positive polarity generated in winding 18 to fire the tube 22 and discharge capacitor 24 is sufficient to provide a high energy pulse of very short duration in the ignition transformer secondary.

If it is desired to reduce the current through the transistor during the period following charge of the condenser 24 and prior to opening of the contacts 10, current feed back to the transistor circuit may be employed as in the circuits now to be described.

In FIG. 2, in which elements corresponding to those of the circuit of FIG. 1 are identified with like reference numbers, current feed back to the base circuit of the transistor 2 is provided by connecting one end of secondary 14 to the base of transistor 2 instead of to the negative terminal of the battery. With this arrangement when the contacts 10 close the charging current through winding 14 decreases the potential at the base of train sistor 2 and thereby increases the current through the transistor during such period. When condenser 24 is charged the current through the transistor will decrease to a low value and be maintained at such low value until the breaker contacts open.

The circuit of FIG. 3 differs from that of FIG. 2 only in the addition of a second transistor 28 to the base of which one end of the winding 14 is connected. The emitter terminal of transistor 28 is connected to the base of transistor 2 and the collector terminal of transistor 28 is connected to the negative terminal of the battery 4. With the arrangement of FIG. 3 transistors of lower gain may be employed because of the current amplification obtained by the use of two transistors. It Will be clear that when the breaker contacts close transistor 28 will start to conduct causing conduction through transistor 2, current flow through the primary of transformer 6 and consequent charging of condenser 24 through the rectifier 16. The charging current, as in the embodiment of the invention illustrated in FIG. 2, decreases the potential at the base of transistor 28 causing increased conduction by the two transistors during the charging period.

The system of FIG. 4 differs from that of FIG. 2 in that a transformer 30 is provided for coupling the secondary 14 of the transformer 6 to the base circuit of the transistor 2. The operation of the circuit is substantially identical with that already described in connection with FIG. 2.

In FIG. the current feed back to the transistor base circuit is shown as in FIG. 2. In FIG. 5 additional current for the spark is obtained by the provision of a second capacitor 32 which is connected to the secondary of the ignition coil 26 and, through a high frequency choke 34, to the cathode of the diode 16. In this embodiment of the invention the secondary winding of the spark coil should be reversely wound as indicated by the dots associated with the coil so that following discharge of condenser 24 through the primary winding the charge on condenser 32 will discharge in the same direction through the secondary winding as the current induced by the discharge of condenser 24. Consequently, following the surge of current through the secondary of the spark coil due to discharge of condenser 24 through the primary winding, condenser 32 discharges to augment the current of the spark. Choke coil 34 prevents discharge of capacitor 32 through tube 22 during its period of conduction. Obviously the expedient illustrated in FIG. 5 for augmenting the spark current could as well be incorporated in the circuit of FIG. 4 or in that of FIGS. 1 or 3.

In the circuit of FIG. 6 a pulse forming network is shown connected between the primary of the ignition coil 26 and the cathode of rectifier 16. The pulse forming network comprises three condensers 36, 38 and 40 each connected to one end of the primary Winding of coil 26, an inductor 42 bridged across the other terminals of condensers 36 and 38 and an inductor 44 bridged across the other terminals of condensers 38 and 40. The junction of inductor 42 and the other terminal of condenser 36 is connected to the cathode of diode 16 and to the anode of tube 22.

In the above circuit condenser 36 is connected as is condenser 24 in the circuits heretofore described. Accordingly, when diode 16 conducts condenser 36 will immediately begin to charge. During this charge condenser 38 begins to charge and subsequently, during charging of condensers 36 and 38, condenser 40 begins to charge. The discharge of the condensers 36, 38 and 40 through thyratron 22 will similarly be consecutive and overlapping to provide a substantially square shaped wave which prolongs the duration of the spark to insure that the spark will be adequate to explode all the gases in the engine cylinders. Such type of spark is advantageous in that it hastens the spreading of the combustion throughout the cylinder.

The invention has now been described in connection with several embodiments thereof. It will be apparent that various alternative combinations of the elements of the circuits shown in the drawings could be made without departing from the spirit of the invention or the scope of the accompanying claims. As heretofore indicated, the expedient illustrated in FIG. 5 which provides extra storage capacity to give additional current for the spark could be combined with the circuits of any one of the other figures and similarly the pulse forming cir- 4 cuit elements of FIG. 6 could be utilized in the circuits of the other figures.

What I claim is:

1. In an ignition circuit for internal combustion engines having a car carried battery, breaker contacts and an ignition coil connected to the car distributor contact, the combination comprising a current amplifier having an input circuit connected in series with the breaker contacts across the battery and an output circuit including the primary winding of a step-up transformer, said transformer including first and second secondary windings, a storage capacitor connected through a rectifier to said first secondary Winding to be charged upon closure of the breaker contacts, and a gas thyratron connected to discharge said capacitor through the ignition coil when rendered conductive, said second secondary Winding being connected to said thyratron for controlling conduction therethrough so as to cause discharge of said capacitor upon opening of the breaker contacts.

2. The combination according to claim 1 wherein said current amplifier is a transistor and wherein a resistor is connected between the base of the transistor and the breaker contacts.

3. The combination according to claim 2 including means responsive to charging current flowing in said first secondary winding for augmenting current flow through said transistor.

4. The combination according to claim 3 wherein said last mentioned means comprise a connection between said first secondary winding and the base of said transistor.

5. The combination according to claim 3 wherein said last mentioned means comprise a transformer having one end of its primary winding connected to the base of said transistor and its other end connected to one end of said resistor and its secondary winding connected in series with said first secondary winding of said step-up transformer.

6. The combination according to claim 1 wherein said current amplifier comprises a first and a second transistor, the emitter of said first transistor being connected to one terminal of the battery, the collector for said first transistor being connected to one end of the primary of said step-up transformer and the base of said first transistor being connected to the emitter of said second transistor, the collector of said second transistor being connected to the other terminal of the battery and the base of the second transistor being connected through a resistor to the breaker contacts.

7. The combination according to claim 6 including means responsive to charging current flowing in said first secondary winding for augmenting current flow through said transistors.

8. The combination according to claim 7 wherein said last mentioned means comprise a connection between said first secondary winding and the base of said second transistor.

9. In an ignition circuit for internal combustion engines having timed pulsing means and an ignition coil, the combination comprising a step-up transformer, said transformer including a primary winding and first and second secondary windings, a transistor amplifier having an input circuit connected to said pulsing means and an output circuit connected to said primary winding, a storage capacitor connected through a rectifier to said first secondary winding to be charged when said amplifier is pulsed by said pulsing means, and a switch device connected to discharge said capacitor through the ignition coil when rendered conductive, said secondary winding being connected to said switch device for controlling con duction therethrough so as to cause discharge of said capacitor upon reduction of current in said primary winding.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Randolph Jan. 14, 1936 Randolph Feb. 11, 1936 6 Randolph June 4, 1940 6 Short July 12, 1949 Short et al. Jan. 2, 1951 Orosby Oct. 30, 1956 Giacoletto Mar. 17, 1959 Lawson Aug. 11, 1959 

